Add sticky event deliver logic after reRegistration

Current logic fails with this scenario:
we have class A with subclass B.
and we create method "onEvent(A a);" in class Subscriber
So if Subscriber is registered and we execute postSticky(new B());, then
onEvent method of Subscriber will be called (it is ok).
But if Subscriber call unregister and then registerSticky if will not
receive event B (this is bug).
p.s. but if Subscriber has "onEvent(B b);" it will.